The 29-year-old moved into the quarter-finals as he defeated his Egyptian opponent in four sets at the University Club of Chicago, with the final score standing at 11-6, 11-8, 6-11, 11-3.

Rösner hit a flurry of winners during the 47-minute encounter against the three-time world champion, who had won all six matches played between the two previously.

“That’s one of, if not the, biggest wins of my career,” the German said.

“You never know what to expect from Ramy, he’s such a unique player.

“I think he played well today, but I managed to keep him away from the centre of the court and it was one of those days where you step on court and have a good feeling.”

Up next for Rösner is another Egyptian, Ali Farag, after he beat Peru’s Diego Elias 6-11, 11-9, 5-11, 11-6, 11-6 in a lengthy 69-minute match.

Marwan El Shorbagy also needed five sets to see off South Africa’s Stephen Coppinger 11-4, 9-11, 12-10, 4-11, 11-6 and the Egyptian fifth seed will face his brother and world number one Mohamed, who won 11-9, 11-6, 11-8 against Mexican Cesar Salazar, in the last eight.

In the women’s draw, top seed Nour El Sherbini of Egypt eased through to the quarter-finals with a 11-2, 11-7, 11-8 win over England’s Victoria Lust.

The world number one will now meet two-time Commonwealth Games women’s singles champion Nicol David in the next round.

David set-up the tie after beating English player Emily Whitlock 11-7, 11-6, 11-7 in 34 minutes.

Fourth seed Camille Serme also progressed after the French player knocked out Wales’ Tesni Evans 8-11, 11-8, 11-6, 13-11.

Alison Waters of England, seeded eighth, will play Serme in the last eight after winning 11-9, 11-7, 11-13, 11-6 against Hong Kong’s Joey Chan.

Competition in Chicago is due to continue until March 1.